Update: No, this does not have anything to do with ethereal so to speak

So far I've determined that, turning off other world gen mods such as nether and bedrock and a few other non world gen mods doesn't seem to affect the crash issue. In fact, I turned off ethereal and reloaded the default_game and placing the apple tree sapling still crashes the server.

Update 2:

I have turned off all mods but placing the default:sapling on default:dirt_with_grass still crashes the server.

I made a singleplayer server world v7 4.16 and turned on ethereal and placed the sapling and it did not crash the game for me. So, again, what was done appears to be done at this point.

Update: No, this does not have anything to do with ethereal so to speak

So far I've determined that, turning off other world gen mods such as nether and bedrock and a few other non world gen mods doesn't seem to affect the crash issue. In fact, I turned off ethereal and reloaded the default_game and placing the apple tree sapling still crashes the server.

Update 2:

I have turned off all mods but placing the default:sapling on default:dirt_with_grass still crashes the server.

I made a singleplayer server world v7 4.16 and turned on ethereal and placed the sapling and it did not crash the game for me. So, again, what was done appears to be done at this point.

So, yes, I am basically out of ideas.

My bad, I was not using 0.4.16 stable minetest_game. It doesn't crash the server now. Probably should see some general improvement since I was using the wrong once since day on.